Fix dotnet#32: SelectAll() is not available when SelectionUnit="Cell"

Author: tom-englert

DataGridExtensions/DataGridFilterHost.cs

@@ -185,13 +185,13 @@ private void DataGrid_Loaded([NotNull] object sender, [NotNull] RoutedEventArgs
             headersPresenter?.SetValue(KeyboardNavigation.TabNavigationProperty, KeyboardNavigationMode.None);
         }
 
-        private void DataGrid_SelectAll(object sender, [NotNull] ExecutedRoutedEventArgs e)
+        private void DataGrid_SelectAll([CanBeNull] object sender, [NotNull] ExecutedRoutedEventArgs e)
         {
             e.Handled = true;
 
             if (!_isFilteringEnabled || (DataGrid.Items.Count > 0))
             {
-                if (DataGrid.SelectionMode != DataGridSelectionMode.Single)
+                if (DataGrid.CanSelectAll())
                 {
                     DataGrid.SelectAll();
                 }
@@ -205,9 +205,9 @@ private void DataGrid_SelectAll(object sender, [NotNull] ExecutedRoutedEventArgs
             }
         }
 
-        private void DataGrid_CanSelectAll(object sender, CanExecuteRoutedEventArgs e)
+        private void DataGrid_CanSelectAll([CanBeNull] object sender, [NotNull] CanExecuteRoutedEventArgs e)
         {
-            e.CanExecute = (DataGrid.SelectionMode != DataGridSelectionMode.Single) || (DataGrid.Items.Count == 0);
+            e.CanExecute = DataGrid.CanSelectAll() || (DataGrid.Items.Count == 0);
         }
 
         private void Columns_CollectionChanged([NotNull] object sender, [NotNull] NotifyCollectionChangedEventArgs e)

DataGridExtensions/ExtensionMethods.cs

@@ -237,6 +237,19 @@ public static IList<DataGridCellInfo> GetVisibleSelectedCells([CanBeNull] this D
                 .ToArray();
         }
 
+        /// <summary>
+        /// Determines whether it's safe to call "DataGrid.SelectAll()".
+        /// </summary>
+        /// <param name="dataGrid">The data grid.</param>
+        /// <returns>
+        ///   <c>true</c> if it's safe to call "DataGrid.SelectAll(); otherwise, <c>false</c>.
+        /// </returns>
+        public static bool CanSelectAll([NotNull] this DataGrid dataGrid)
+        {
+            return (dataGrid.SelectionMode != DataGridSelectionMode.Single && dataGrid.SelectionUnit != DataGridSelectionUnit.Cell);
+        }
+
+
         [NotNull, ItemCanBeNull]
         private static IEnumerable<T> Repeat<T>([NotNull, ItemCanBeNull] ICollection<T> source, int count)
         {

DataGridExtensionsSample/MainWindow.xaml

@@ -144,6 +144,7 @@
             </TextBlock>
           </DockPanel>
           <DataGrid ItemsSource="{Binding Source={StaticResource SortedItems}}" AutoGenerateColumns="False" FrozenColumnCount="2"
+                    SelectionUnit="Cell"
                     dgx:DataGridFilter.GlobalFilter="{Binding ExternalFilter}"
                     dgx:DataGridFilter.IsAutoFilterEnabled="True"
                     dgx:Tools.ApplyInitialSorting="True"